Explosively released nut



Feb. 3, 1959 N. C. PARRISH EXPLOSIVELY RELEASED NUT Filed June 8. 1953 Fig.5

2 Sheets-Sheet 2 2,871,750 mQLosIvELY RELEASED NUT Norman Charles Parrish, Redondo Beach, Calif., assignor to Northrop Aircraft, Inc., Hawthorne, Calif, a corporation of California Application June 8, 1953, Serial No. 360,216 3 Claims. 01. ss-32 This invention relates to releasable fasteners and more particularly to a nut, washer, or like element which may be instantly released from an associated member with which it.is associated by means of an explosive charge.

Explosive charges utilized in connection with cooperating structures are presently known for effecting the quick release of one piece of structure from another, such devices are utilized extensively in the aircraft industry for effecting the quick release of closures, canopies, auxiliary gas tanks, bombs, and etc. positioned at a remote location. Such quick release means may, of course, be utilized in any type of installation where instantaneous release of assembled parts is required.

Briefly the fastener of the present invention comprises a novel element cooperating with an associated member, the element having an explosive charge positioned interiorly of a wall portion thereof and a longitudinally extending groove positioned diametrically opposite the charge, also in a wall portion. Detonation of the explosive charge, accompanied by the resulting expanding gases, cause the element to separate longitudinally into two approximately equal parts thereby freeing the associated member. The associated member being subsequently automatically ejected from structure with which it in turn may be associated by the action of a preloaded compressed spring.

An object of the present invention is to provide a novel element adapted to cooperate with an associated member, the element incorporating an explosive charge whereby it may be instantaneously released from the associated member and also incorporating means whereby forces effecting its releases are concentrated.

Another object is to provide an instantaneous releasable fastener comprising a pair of engageable members and resilient means for ejecting from structure, with which the fastener may be associated, one of the members momentarily after its release by the other member.

Another object is to provide an instantaneous releasable element which is simple and compact in design and construction and easily manufactured, -in fact may be easily constructed from any conventional nut, washer or like element.

These and other objects will become more apparent from the following description and drawings in which like reference characters denote like parts throughout the several views. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and not a definition of the limits of the invention, reference being had for the purpose to the appended claims.

In the drawing:

Figure 1 is a longitudinal sectional view of an installation utilizing the novel nut of the present invention.

Figure 2 is an end elevational view of the installation shown in Figure l, viewed from the left end thereof.

2,871,755 Fatented Feb. 3, 1959 Figure 3 is a sectional view of the nut of Figure 1, taken on the line 3-3 of Figure 2.

Figure 4 is a view similar to Figure 2 showing the manner in which the nut separates.

Figure 5 is a longitudinal sectional view of another embodiment of the present invention.

Figure 6 is a longitudinal sectional view of still another embodiment of the present invention.

Referring to the drawing for a detailed description .of a preferred embodiment of the present invention,

Figure 1 shows a releasable fastener 11 comprising a conventional bolt 12 and associated nut 13. In the present embodiment the fastener is utilized to secure frame members 14 and 15 together so that one may be instantly released from the other.

Members 14 and 15 are provided with transverse webs 16 and 17, respectively, the webs having aligned apertures through which the shank of bolt 12 passes. The head of the bolt is maintained in spaced relation with respect to web 17 by means of a helical wound preloaded compression spring 18 which surrounds the shank of the bolt. In the assembled position of frame members 14- and 15, spring 18 may be completely compressed or the various turns may be separated, as shown in Figure 1, according to the force required to be exerted on the frame members; The function of the spring will be explained presently.

The nut- 13 is provided with a bore 19 adapted to contain a suitable explosive or combustible charge 20. The bore is positioned so that its length is parallel with the axis of the threaded portion of the nut and is located on radius thereof approximately midway between the threaded portion and an apex of the nut, as shown in Figure 2.

The bore enters the nut through its end face, adjacent washer 21, and terminates short of its other end. Positioning the bore 19 as described permits it to have a larger diameter than if located elsewhere in the wall of the nut, accordingly it accommodates a larger explosive charge. The explosive charge 20 is maintained in the bore 19 by means of suitable wadding 22 which closes the open end of the bore. Suitable electric leads 23, for detonating the explosive charge, pass through one of the hexagon faces of the nut and are imbedded in the charge in such a manner that it will be detonated when electrical current is caused to flow through the leads. A V-shaped groove 24 is formed in the wall of the nut diametrically opposite bore 19, the groove is further located so that its length is parallel with the length of the bore and is of such a depth that it ex tends through the threads of the nut and penetrates the wall thereof an appreciable amount. The groove has the effect of concentrating the stress, exerted by the explosive charge tending to separate the nut, as it materially reduces the nuts cross-sectional area at this point.

For purposes of illustration, it is assumed that frame member 15 is fixedly supported by any suitable type of structure (not shown), frame member 14 being attached to member 15 by fastener 11 which constitutes its only means of support, accordingly if the fastener is removed member 14 will be free to fall away from member 15 under the influence of' gravity or other forces. Prior to installing the fastener 11 in the manner shown in Figure 1, the leads 23, explosive charge 20, and wadding 22 are installed in bore 19 of the nut, the leads 23 are then secured to a source of electric current (not shown) after installation. At such time as it is desired to separate member 14 from member 15, an electric current is caused to fiow through leads 23 resulting in the detonation of charge 19. Forces exerted by the expanding gases of the explosive charge are sufiicient to cause the wall of the nut to separate longitudinally, a indicated at A in Figure 4. As the wall of the nut separates slightly at A its Wall also separates longitudinally at B due to groove 24 which weakens. ,the wall and. encourages a break at this location. -With the wall of the nut separated at A and B, the nut is "free to fall away and free bolt 12. The spring 18 being preloaded exerts a force against the head of the bolt ejecting its shank from the aforementioned aligned apertures in webs i6 and 17. Member 14 is then completely freed from member i and may fall therefrom in accordance with forces acting thereon.

Figure 5 shows another embodiment of the fastening device of the present invention, in this figure a rivet 25, provided with a reduced end portion 26, and washer ele ment 27 replace thebolt 12 and nut '13, respectively, of Figures 1 to 4. Bore 1'9, containing the explosive charge Ztl, and groove 24 are of the same configuration, location and function in an identical manner as disclosed in connection with the previously described embodiment, accordingly a further description of these parts is not deemed necessary. As mentioned above the end portion 26 of the rivet is less in diameter than its main shank portion, this permits its extreme end portion 28 to be peened over, thereby securing element 27. The peened portion of the rivet is of less diameter than the diameter of the aligned apertures in webs 16 and 17 so that the rivet may be ejected by spring 29 after its release by element 27. In this embodiment the spring is shown as being constructed of square stock, the various turns of which are in contacting relationship. Although the rivet shown in Figure 3 is peened over, indicating it is made of mild steel, it may also be a Hi-Sheer rivet, if a rivet of the latter type is utilized a collar (not shown) will replace the peened portion 28.

Still another modification is shown in Figure 6, this modification is very similar to that shown in Figure 5 except a locking ring 34} is utilized to retain washer 27 in its relative position on rivet 25. In this embodiment a conical type spring 31 is utilized to eject the rivet from the aligned apertures in webs 16 and 17 after its release.

While in order to comply with the statute, the invention has been described in language more or less specific as to structural features, it is to be understood that the inveniton is not limited to the specific features shown, but that the means and construction herein disclosed comprises the preferred form of several modes of putting the invention into effect, and the invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.

What is claimed is:

1. In an explosive breakaway attachment: fastening element having spaced parallel end faces, a plurality of opposed side faces and a threaded bore extending between an opening on both of said end faces; portions of said '4 element define an elongated cavity having a longitudinal axis of symmetry; said cavity being spaced from said bore, extends to and opens on one of said end faces, and terminates short of the other of said end faces; an explosive charge positioned in said cavity; other portions of said element defines at least one aperture therein extending between one of said side faces and said cavity; wire means passing through said aperture whereby said explosive charge may be detonated when desired; still other portions of said element defines an elongated V-shaped groove which extends between said end faces and opens into said bore; and the axis of said cavity and the apex of said groove being parallel to the axis of said bore and said cavity being located on the side of said bore diametrically opposite said groove.

2. In an explosive breakaway attachment as set forth in claim 1; further characterized in that the apex of said groove extending radially outwardly from the axis of said bore penetrating the threads therein and a portion of the solid wall of said element.

3. In an explosive breakaway attachment adapted to releasably secure at least two associated parts together by portions of said attachment passing through aligned aperture formed in said parts, the combination cornprising: an elongated member having a threaded shank portion and a head portion; an element having parallel end faces and a plurality of side faces surrounding said shank in threaded engagement; portions of said element define a cavity which is spaced from said shank, opens on one of said end faces, and terminates short of the other one of said end faces; an explosive charge positioned in said cavity; portions of said element define at least one aperture which extends between one of said side faces and said cavity; wire means passing through said aperture whereby said explosive charge may be detonated when desired; still other portions of said element define a V-shaped groove extending between said end faces and opens into said bore at a location diametrically opposite said shank from said cavity; and a compression type helical spring surrounding said shank at a location between said head portion and the most adjacent one of said two associated parts.

References Cited in the file of this patent UNITED STATES PATENTS 414,519 Gladding Nov. 5, 1889 1,434,558 Merryman Nov. 7, 1922 1,609,772 Rank Dec. 7, 1926 2,064,377 Gordon Dec. 15, 1936 2,316,695 Jaifa Apr. 13, 1943 2,556,672 Bergh et al. June 12, 1951 FOREIGN PATENTS 694,019 Germany July 24, 1940 875,292 France June 15, 1942 

